The best solution is a dedicated laptop with the BMW dealer software. It's amazing with full diagnostics and repair guide built in. It's somewhat problematic to get it configured correctly. The latest package is called ISTA/INPA or Rheingold.

For easy simplicity with all the features most people need is BMW Scanner 1.4 on eBay for ~$20. It needs a laptop with XP. An old one is fine. This is what I use most of the time.

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2005 X5 4.4i SterlingGrau, Sport Package, DSP
Build 3/12/2005